Methods for exchanging devices

ABSTRACT

A method for replacing a first sheath, whose distal end is positioned inside a vessel and whose proximal end is positioned outside the skin of a patient, with a second sheath may involve inserting a dilator over a guidewire and into the first sheath until a distal end of the dilator and a distal end of the guidewire are positioned inside the vessel. The dilator may be hubless or include a removable hub, and may define an external channel configured to receive a second guidewire. The method may further involve removing the first sheath, thereby leaving the dilator and the guidewire in place. After removing the first sheath, a second sheath may be passed over the dilator and the guidewire until the distal end of the second sheath is positioned inside the vessel. The method may further involve removing the dilator and the guidewire, leaving the second sheath in place.

CROSS-REFERENCE TO RELATE APPLICATION

This application is a continuation-in-part of pending U.S. applicationSer. No. 15/646,206, filed Jul. 11, 2017, entitled “METHODS FOREXCHANGING DEVICES,” the entirety of which is hereby incorporated byreference for all purposes.

TECHNICAL FIELD

This application relates generally to methods for exchanging devicesduring vascular procedures. Implementations involve, but are not limitedto, the exchange of devices such as sheath devices, including using aguidewire and a dilator configured to pass over the guidewire.

BACKGROUND

Percutaneous procedures often involve accessing vasculature withelongated instruments, e.g., catheters, deployed in an ordered sequence.Common vasculature access points for such procedures include the femoralartery in a patient's groin area and the radial artery in the patient'sforearm, each of which provides direct access to the central vasculaturesystem, including the central venous system. Entry into the femoral andradial arteries is often accomplished via the Seldinger technique, whichinvolves using a hollow needle to poke through a patient's skin,subcutaneous tissue and targeted vessel wall, thereby creating apuncture hole through each layer. After the needle poke, a guidewire isinserted through the needle until a distal end of the guidewire passesthrough the puncture hole and protrudes into the vessel lumen. Theneedle may then be removed and additional instrumentation inserted atthe same access point into the vessel along the track provided by theguidewire.

Depending on the specific procedure being performed and thecharacteristics of the patient being operated on, proceduralinstrumentation may be inserted directly over the guidewire in theabsence of an introducer assembly (also known as the “bareback method”).More commonly, however, an introducer assembly is first inserted overthe guidewire and fed into the vessel. Such an assembly may include anintroducer sheath having a hemostasis valve at its proximal end andcoupled with a dilator having an integrated proximal hub. Once a distalportion of the introducer sheath is positioned within the vessel, thedilator is removed by disengaging its proximal hub from the sheath'shemostasis valve and pulling on the hub, leaving the sheath and theguidewire in place to feed a guiding catheter into the vessel. Theguiding catheter may be configured to channel a procedural device orassembly, such as a transcatheter aortic valve replacement (“TAVR”)assembly, into and through the vessel to a desired treatment site. Insuch cases, deployment of the aortic valve replacement is followed byremoval of the procedural assembly (minus the valve) and the guidingcatheter, leaving the introducer sheath and guidewire in place.

Removal of the introducer sheath and guidewire would leave an exposedpuncture hole in the vessel wall, causing internal and externalbleeding. To avoid or minimize the effects of this result, the puncturehole created through the vessel wall must be sealed. A common method ofcontrolling the puncture hole is to maintain external pressure (e.g.,human hand pressure) over the vessel until the puncture seals by naturalclot formation processes. This method of puncture closure typicallytakes between 30 and 90 minutes, can be uncomfortable for the patient,can result in excessive restriction or interruption of blood flow, andcan consume costly time and effort on the part of the hospital staff.Another method of controlling the puncture hole is to implant a sealingdevice or assembly over the puncture. This method can involve exchangingthe procedural introducer sheath with a second, different-sizedintroducer sheath configured specifically for guiding the sealing deviceor assembly to the vessel.

SUMMARY

Some existing methods of exchanging the procedural introducer sheathwith the second, different-sized introducer sheath rely solely on theguidewire to channel the second introducer sheath to the vessel andthrough the puncture hole. The procedural introducer sheath is pulledproximally over the guidewire, and then the second introducer sheath isinserted over the guidewire. The present inventor recognizes that thesemethods, however, increase the risk of losing the original vessel accesspoint due to a guidewire lacking sufficient stiffness to support thesecond introducer sheath or movement of the guidewire, an outcome morelikely when operating on patients who may have a thicker layer of fattissue between the targeted vessel and the skin. Additionally, thesemethods can be associated with excessive patient blood loss due to thesmall cross-sectional size of the guidewire relative to the puncturehole. Other methods, such as that disclosed in U.S. Pat. No. 7,094,209,which is incorporated by reference herein in its entirety, utilize astiff, lumenless guide rod in lieu of a guidewire to facilitate sheathexchange. The present inventor further recognizes that such methods,however, are vulnerable to vessel perforation since the guide rod'sdistal end cannot track to a parallel orientation relative to the vesselwall through advancement over a guidewire. They also increase the riskof losing the vessel access point due to the typically short length ofthe guide rod. There is thus a need in the art for apparatuses andmethods configured to exchange vascular sheaths while maintaining theoriginal vessel access point and without perforating the vessel wall.

In some embodiments, a method for replacing a first sheath, whose distalend is positioned inside a vessel and whose proximal end is positionedoutside the skin of a patient, with a second sheath may involveinserting a dilator over a guidewire and into the first sheath until adistal end of the dilator and a distal end of the guidewire arepositioned inside the vessel. The method may further involve removingthe first sheath, thereby leaving only the dilator and the guidewire inplace; passing the second sheath over the dilator and the guidewireuntil a distal end of the second sheath is positioned inside the vessel;and removing the dilator and the guidewire, thereby leaving only thesecond sheath in place.

In some examples, the dilator may be hubless or include a removable hub(in each case herein where the dilator is referred to as hubless orincluding a removable hub, the dilator may be one, the other, or both)and may define a lumen configured to receive the guidewire. In someembodiments, the dilator may include a middle portion having anapproximately constant diameter. A portion of the distal end of thedilator and a proximal end of the dilator may be tapered. In someexamples, the tapered portion of the distal end of the dilator mayinclude a radiopaque band. In some examples, multiple portions of thedilator include a radiopaque element (e.g., radiopaque filler materialimpregnated into a polymer of the dilator portions). In someembodiments, the diameter of the middle portion of the dilator may beapproximately the same size as a puncture hole in the vessel wallcreated during a vascular procedure. The dilator may be of any desiredlength. In some examples, the dilator may be about 30 cm to about 70 cmlong, inclusive. In some embodiments, the dilator may have anapproximately uniform stiffness profile along its length.

In some examples, the first sheath may be a procedural introducer sheathconfigured to channel at least one interventional device to the vessel.The interventional device may include a transcatheter aortic valvereplacement assembly in some implementations. In some examples, thesecond sheath may be a sealing introducer sheath configured to channelan implant assembly to the vessel. The implant assembly may beconfigured to seal the puncture hole created in a wall of the vesselduring the vascular procedure.

In some embodiments, the guidewire may define a lumen and a length thatis greater than the length of the dilator. In some examples, the lengthof the guidewire may be about 30 cm to about 80 cm, inclusive. In someembodiments, the distal end of the guidewire may extend at least about 5cm or at least about 10 cm within a lumen of the vessel after placementtherein. In some examples, an external diameter of the guidewire may beabout 0.01 inches to about 0.04 inches, inclusive. In variousimplementations, the vessel may comprise a portion of the femoral arteryor the radial artery. In some examples, the distance between an outersurface of the vessel wall and the skin of the patient may be about 1 cmto about 10 cm.

In some examples, the dilator may define an external channel configuredto slidably receive a channel guidewire. In some embodiments, uponremoving the first sheath, the channel guidewire may remain inserted orseated within the external channel defined by the dilator. In someexamples, passing the second sheath over the dilator and the guidewiremay further comprise removing the channel guidewire from the externalchannel using the second sheath. In some embodiments, removing thedilator and the guidewire may further comprise leaving the channelguidewire in place within the patient. In some embodiments, a portion ofthe distal end of the dilator and a proximal end of the dilator may betapered and the external channel may extend onto the distal and proximalends. The guidewire and the channel guidewire may be substantiallyequally dimensioned in some embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, like numerals can be used to describe similar featuresand components throughout the several views. The drawings illustrategenerally, by way of example but not by way of limitation, variousembodiments discussed in this patent document:

FIGS. 1-5 are schematic illustrations of steps in a sheath exchangeprocess in accordance with embodiments of the present teachings.

FIG. 6 is a schematic illustration of a dilator used in a sheathexchange process in accordance with embodiments of the presentteachings.

FIG. 7 is a schematic illustration of a magnified view of an end portionof the dilator shown in FIG. 6.

FIG. 8A is a schematic illustration of a dilator defining an externalchannel, which may be used in a sheath exchange process in accordancewith embodiments of the present teachings.

FIG. 8B is another schematic illustration of the dilator shown in FIG.8A.

FIG. 8C is another schematic illustration of the dilator shown in FIG.8A.

FIGS. 9-13 are schematic illustrations of steps in another sheathexchange process in accordance with embodiments of the presentteachings.

FIG. 14 is a schematic illustration of an introducer kit including anaccess needle, a dilator, a guidewire, and a delivery assembly usedaccording to at least one embodiment of the present teachings.

FIG. 15 is a schematic illustration of another introducer kit includingan access needle, a dilator defining an external channel, twoguidewires, and a delivery assembly used according to at least oneembodiment of the present teachings.

The drawing figures are not necessarily to scale. Certain features andcomponents may be shown exaggerated in scale or in schematic form, andsome details may not be shown in the interest of clarity andconciseness.

DETAILED DESCRIPTION Definitions

Certain terms are used throughout this patent document to refer toparticular features or components. As one skilled in the art willappreciate, different people may refer to the same feature or componentby different names. This patent document does not intend to distinguishbetween components or features that differ in name but not in function.For the following defined terms, certain definitions shall be appliedunless a different definition is given elsewhere in this patentdocument.

The terms “distal” and “proximal” refer to a position or directionrelative to a treating clinician. “Distal” and “distally” refer to aposition that is distant, or in a direction away, from the clinician.“Proximal” and “proximally” refer to a position that is closer to, or ina direction toward, the clinician.

The term “patient” refers to a mammal and includes both humans andanimals.

All numeric values are assumed to be modified by the term “about,”whether or not explicitly indicated. The term “about” refers to a rangeof numbers that one of skill in the art would consider equivalent to therecited value (e.g., having the same function or result). In manyinstances, the term “about” can include numbers that are rounded to thenearest significant figure.

The recitation of numerical ranges by endpoints includes all numbers andsub-ranges within and bounding that range (e.g., 1 to 4 includes 1, 1.5,1.75, 2, 2.3, 2.6, 2.9, etc. and 1 to 1.5, 1 to 2, 1 to 3, 2 to 3.5, 2to 4, 3 to 4, etc.).

As used in this specification and the appended claims, the singularforms “a”, “an”, and “the” include plural referents unless the contentclearly dictates otherwise. As used in this specification and theappended claims, the term “or” is generally employed in its senseincluding “and/or” unless the content clearly dictates otherwise.

Example Applications of the Present Teachings

Vascular procedures are performed throughout the world and requireaccess to a blood vessel of the vasculature system through a puncture.FIGS. 1-5 and 9-13 include schematic illustrations of a puncture in awall of a blood vessel (e.g., a femoral or radial artery or a desiredvein or other vessel). The vessel is shown in cross-section passingbeneath the skin and subcutaneous tissue of a patient. The vessel hasbeen accessed by way of a percutaneous surgical procedure, which hasresulted in an access path consisting of a tissue tract and thepuncture. For example, the tract and puncture may have been formed byinserting an introducer assembly into a lumen of the vessel.

The present methods and systems can be used to exchange sheaths used inpercutaneous procedures to introduce catheters and other intravasculardevices into the vasculature. More particularly, disclosed methods andsystems involve using at least one guidewire and a hubless orremovable-hubbed, over-the-wire dilator to facilitate the exchange ofvarious sheath devices while maintaining a vascular access point andavoiding vessel wall perforation. Some embodiments can involve the useof a hubless or removable-hubbed dilator that defines an externalchannel configured to receive a channel guidewire in addition to anaxial guidewire received within a dilator lumen. Specific examples mayinvolve the replacement of a procedural sheath, such as an introducersheath for a TAVR assembly, with an introducer sheath configured toreceive a vessel wall sealing assembly and/or implant; however, themethods disclosed may be readily applicable to a wide range of sheathdevices employed during a wide range of vasculature procedures.Additional procedures requiring introducer sheaths include, for example,mitral valve repair or replacement, tricuspid valve repair orreplacement, abdominal aortic aneurysm repair, thoracic aneurysm repair,transcutaneous aortic valve implantation (“TAVI”), endovascular aneurysmrepair (“EVAR”), trans-septal occluder implantation and implantation ofa variety of percutaneous ventricular-assist devices.

Sheath Exchange Methods, Systems and Devices:

FIG. 1 depicts a cross-sectional view of a blood vessel and surroundingtissue at the starting point of an example method described herein. Asshown, a first sheath 102 has been inserted through an access path intothe blood vessel of a patient. The access path, and thus the firstsheath 102 inserted therethrough, extends through the skin 104,subcutaneous tissue 106, and blood vessel wall 108, such that a distalend 110 of the first sheath protrudes into a lumen 112 of the bloodvessel 113 through a puncture hole in the vessel wall. Opposite thedistal end 110, the first sheath 102 includes a proximal end 114 havinga hemostasis valve 116, both external to the patient. As further shown,a first, axial guidewire 118 may be positioned within the first sheath102 such that a distal end 120 of the guidewire protrudes from thedistal end 110 of the sheath into the lumen 112 of the blood vessel 113.

The particular size and configuration of the first sheath 102 may varyaccording to the specific intravascular procedure being performed. Forexample, the first sheath may be a procedural introducer sheath used tofacilitate the insertion and removal of one or more surgicalinstruments, e.g., a guiding catheter, employed during a procedure. Thefirst sheath may reduce lateral and axial movement of the guidingcatheter used during a vascular procedure relative to the blood vesselwall, thereby reducing or eliminating vessel spasm. Particularembodiments may include an introducer sheath configured to feed a TAVRassembly through the vessel puncture hole. The length of the firstsheath may vary depending on the depth of the targeted vessel 113relative to the skin 104, said depth ranging from about 1 cm to about 10cm in some embodiments, or depths less or greater than this range. Thefirst sheath defines a lumen, the diameter of which may also vary,configured to receive various elongated vascular instruments. While thefirst sheath 102 shown in FIG. 1 is generally cylindrical, anycross-section may be used (and the cross-section can vary along thelength), and the shape of the sheath may also vary, defining convergingand/or asymmetrical tip portions, for example.

The size and configuration of the guidewire 118 may also vary. In someexamples, a hollow guidewire defining a lumen may be used. In otherembodiments, the guidewire may be solid. The diameter of the guidewiremay vary depending on the diameter of the vessel lumen 112 and/or thediameter of the other instruments employed during the operation.Specific embodiments may include a guidewire having a diameter rangingfrom about a 0.01 in. to about 0.04 in., about 0.013 in. to about 0.038in., about 0.015 in. to about 0.02 in., or about 0.018 in. The length ofthe guidewire may also vary, including ranging from about 30 cm to about270 cm, about 30 cm to about 80 cm, about 30 cm to about 70 cm, about 35cm to about 45 cm, or about 55 cm to about 65 cm in various embodiments.Guidewires may have a length about twice as long as the dilator 122shown in FIG. 2, for example. In some examples, the guidewire may definea tapered tip portion at the distal end, which may also be curved toavoid perforation of the vessel wall 108. The guidewire 118 may comprisestainless steel in some embodiments. It is to be appreciated that thedimensions in this paragraph, and in this document, are exemplary only,and any suitable dimensions may be used.

FIG. 2 depicts a subsequent step, prior to removing the first sheath 102from the access path. At this stage, a dilator 122 may be inserted overthe guidewire 118 and through the lumen of the first sheath 102, suchthat a distal end 124 of the dilator protrudes into the vessel lumen112, along with the distal end 120 of the guidewire. A proximal end 126of the dilator 122 may protrude outside the patient's skin 104, beyondthe proximal end 114 of the first sheath 102. The dilator 122 mayfacilitate exchange of the first sheath 102 with a second sheath, andmay thus be referred to as an “exchange dilator.” After placement of thedilator 122 over the guidewire 118, the guidewire may protrude beyondthe distal end of the dilator, extending into the lumen 112, such as ata distance of about 3 cm to about 10 cm or another desired amount. Thisextension of the guidewire beyond the dilator may prevent the dilator122 from perforating the inner vessel wall, as further distaladvancement of the dilator over the guidewire 120 will result in thedistal end 124 of the dilator following the track of the guidewire andaway from the blood vessel wall 108. With the dilator 122 and guidewire118 in place, the first sheath 102 may be removed.

The size and configuration of the dilator 122 may vary. The dilator 122may be hubless in some examples. The dilator 122 may include a removablehub in other examples. The dilator 122 may also define an internal lumenconfigured to receive the guidewire 118, thus configuring the dilator topass over the guidewire during its insertion and removal. In oneembodiment, the dilator is both hubless and configured to pass over theguidewire 118. The dilator generally defines two ends: the distal end124 configured for insertion into the vessel lumen 112, and the proximalend 126 configured to remain outside of a patient's skin 104. In oneembodiment, both the distal end 124 and the proximal end 126 define atapered portion, such that the width of each end narrows to define anopen tip. The tapered portion at the distal end 124 may facilitatepassage into the lumen 112, while a proximal tapered portion may easesheath exchange.

FIG. 3 shows a subsequent step, after removal of the first sheath 102,which may leave only the guidewire 118 and the dilator 122 inserted atthe vessel access point. The distal ends 120, 124 of the guidewire anddilator, respectively, remain inserted within the lumen 112. Without thestructural support provided by the first sheath 102, the dilator andguidewire, together, may maintain a reliable connection to the vesselaccess point through the original puncture hole. The guidewire 118, inparticular, may serve as an anchor to the access point by protruding asufficient distance within the lumen 112. In some examples, theguidewire 118 may extend about 4 cm to about 14 cm, about 6 cm to about12 cm, or about 8 cm to about 10 cm within the lumen 112. By contrast,the first sheath 102 may extend a different amount, or a lesser amount,such as about 2 cm to about 8 cm within the lumen 112. Consistentplacement of the guidewire 118 at the access point may thus provide asafety net that reduces the likelihood of losing the access point in thevessel, even upon movement of the guidewire and even in the absence ofintravascular anchoring traditionally achieved via a curved distal endon one or more of the other instruments employed during a vascularprocedure. This may be advantageous, as relocating the access point canbe difficult, especially when operating on patients that have relativelylarge amounts of fat tissue between the skin 104 and the targeted bloodvessel 113. In some embodiments, the width of the fat tissue containedbetween the skin 104 and the outer surface of the vessel wall 108(opposite the lumen) may range from about 0.5 cm to about 15 cm, about 1cm to about 10 cm, or about 5 cm to about 7 cm. In addition, theguidewire 118 provides a track for additional instruments to follow,thereby preventing or at least reducing the likelihood of suchinstruments perforating the vessel wall 108.

FIG. 4 shows a subsequent step, during which a second sheath 128 isinserted over the dilator 122 and the guidewire 118. The second sheath128 includes a distal end 130 and a proximal end 132 having a hemostasisvalve 134. The second sheath 128 may be inserted until its distal end130 protrudes within the lumen 112. Like the first sheath 102, thesecond sheath 128 may protrude any desired amount, such as about 2 cm toabout 8 cm, within the lumen 112. Because the dilator 122 is hubless orincludes a removable hub, the dilator may remain inserted through thepuncture hole while the second sheath 128 is inserted thereon. With thesecond sheath 128 in place, the guidewire 118 and the dilator 118 may beremoved.

FIG. 5 shows a subsequent step, after removing the guidewire 118 and thedilator 122. At this stage, only the second sheath 128 remains insertedthrough the access path. With the second sheath 128 in place, variousinstruments may be directed into the blood vessel 113. The specificconfiguration of the second sheath 128 may vary. In some examples, thesecond sheath 128 may be used to facilitate the introduction of asealing assembly, device and/or implant used to seal the puncture holein the blood vessel wall 108 created during the vascular procedure. Forexample, the second sheath 128 may be an introducer sheath configured toreceive and insert an implant assembly configured to seal the puncturehole. An example of such an implant assembly and introducer sheath isdisclosed in U.S. Patent Application Publication No. 2016/0228109 toJacobs et al., the contents of which are incorporated by reference intheir entirety herein. The implant assembly may be used to seal variouspuncture sizes, including small, medium and large punctures resultingfrom 8F to 24F introducer sheaths, for example. In some embodiments, thesecond sheath 128 may comprise an integrated part of a tool used to sealthe puncture hole. For tracking the distal placement of the secondsheath 128, a radiopaque marker band may be embedded or otherwiseattached to the sheath.

FIG. 6 illustrates the dilator 122 used in an embodiment of the sheathexchange process described herein. The dilator 122 shown is hubless anddefines two tapered ends 124, 126. In this specific example, both ends124, 126 are identical or nearly identical. In other embodiments, thedistal end 124 may be different than the proximal end 126 to any desiredextent. For example, the distal end 124 may include a pre-formed curve.In some embodiments, the dilator 122 includes a straight, linearconfiguration from its proximal end 126 to its distal end 124. Thedilator 122 defines an internal lumen that spans the length of thedilator for insertion of a guidewire therethrough. The external diameterof the dilator 122 must be small enough to fit within the lumen of thetargeted blood vessel, and the inner diameter must be large enough toaccommodate passage of a guidewire therethrough. In some embodiments,the middle portion of the dilator 122, i.e., excluding the tapered ends,may have an approximately constant outer diameter, which may beapproximately equal to the diameter of the puncture hole defined by thevessel wall 108. In some examples, the outer diameter of the dilator 122may range from about 0.04 in. to about 0.50 in., about 0.05 in. to about0.46 in., about 0.07 in. to about 0.32 in., about 0.08 in. to about 0.12in. The inner diameter defining the lumen of the dilator, including atthe tapered ends, may range from about 0.02 in. to about 0.04 in., about0.02 in. to about 0.03 in., or about 0.025 in. to about 0.038 in. Insome examples, the length of the dilator may be greater than the lengthof the sheaths exchanged according to the processes described herein.For example, in some embodiments, the dilator 122 may have a lengthranging from about 20 cm to about 70 cm, about 30 cm to about 60 cm, orabout 35 cm to about 50 cm. In some embodiments, the dilator 122 may becustomized to be at least about twice as long as the first sheath 102and/or the second sheath 128. The length of the dilator may varydepending on the specific operation being performed and/or the patientreceiving the operation.

The materials comprising the dilator 122 may vary. For example, thedilator 122 may comprise polyethylene and barium sulfate. In someembodiments, the dilator may comprise HDPE, Teflon, and/or Pebax, othermaterials, or combinations of these. The dilator 122 may also include aradiopaque material, e.g., a radiopaque band ranging in length fromabout 3 mm to about 15 mm. The radiopaque material may be positioned ator near the distal tip of the dilator to increase visibility of thedistal end during placement within the blood vessel lumen. A radiopaquetip portion may comprise polyethylene with tungsten. The dilator mayalso be coated with a lubricating material, such as silicone, tofacilitate insertion and removal through the access path and/or one ormore introducer sheaths. The dilator 122 in the embodiment shown has auniform stiffness profile. In some embodiments, one or more portions ofthe dilator, e.g., the distal portion, may have a variable flexibility.For example, a dilator may include a relatively flexible portion at ornear one or both ends. In some examples, only one or even zero ends aretapered. Ends not defining a tapered portion may be bluntly shaped. Theends of the dilator may not be pre-bent in some embodiments, includingthe embodiment shown. In some examples, the dilator further comprises ameasurement scale.

FIG. 7 is a schematic illustration of a magnified view of an end portion(124 or 126) of the dilator shown in FIG. 6. As shown, each end may betapered to define a tip portion.

FIG. 8A is a schematic illustration of another dilator 136 used in anembodiment of a sheath exchange process described herein. Like thedilator 122 shown in FIG. 6, dilator 136 defines an inner lumen 137configured to receive an axial guidewire, e.g., guidewire 118, and adistal end 138 generally opposite a proximal end 140; however, thedilator 136 also defines an external channel 142 extendinglongitudinally along the length or a portion of the length of thedilator. The channel 142 can be configured to slidably receive a secondguidewire during a sheath exchange process, such that the receivedguidewire rests within the channel 142. At certain moments in varioussheath exchange processes, a channel guidewire may rest between thechannel 142 and the inner surface of a sheath, such as sheath 102. Thechannel 142 can have an approximately consistent depth along the lengthof the dilator 136, but can be shallower at the distal and proximal ends138, 140, where the tapered shape of the dilator reduces the externaldiameter thereof. Despite defining the inwardly-protruding channel 142,the dilator 136 can maintain the same or similar diameter as the dilator122 shown in FIG. 6. In various embodiments, the channel 142 can beconfigured to accommodate a guidewire having a diameter of about 0.038inches. In some examples, the channel 142 may be configured toaccommodate a guidewire having a diameter of about 0.01 in. to about0.04 in., about 0.013 in. to about 0.038 in., about 0.015 in. to about0.02 in., or about 0.018 in., or any other desired size guidewire.

FIG. 8B is another schematic illustration of the dilator 136 shown inFIG. 8A. As shown, the channel 142 can define an elongate slot. When inuse, the channel 142 can be oriented as desired by a user by rotatingthe dilator 136, such that the channel and guidewire resting therein arepositioned in the manner necessary to exchange sheaths and/or perform anintravascular procedure.

FIG. 8C is another schematic illustration of the dilator 136, shown inFIG. 8A, illustrating the full length of the channel 142 according to anembodiment, which can define rounded, pointed, squared or otherwiseconfigured ends within the distal 138 and proximal 140 ends of thedilator.

FIG. 9 depicts a cross-sectional view of a blood vessel and surroundingtissue at the start of another example method described herein, showingthe same anatomical features depicted in FIGS. 1-5. The first sheath 102has been inserted through an access path, such that its distal end 110protrudes into the lumen of the blood vessel. In addition to the firstguidewire 118 positioned within the first sheath 102, a second, channelguidewire 152 has been positioned within the first sheath, such that itsdistal end 154 also protrudes into the lumen of the blood vessel. Thesize and configuration of the channel guidewire 152 may be the same ordifferent than that of the first guidewire 118. In some examples, thechannel guidewire 152 may have a diameter of about 0.038 in. Any otherdesired dimensions may be used.

FIG. 10 depicts a subsequent step, prior to removing the first sheath102 from the access path. At this stage, the dilator 136 may be insertedover the first guidewire 118, but not the channel guidewire 152, suchthat the channel guidewire slides within the channel 142 defined by thedilator 136. In this manner, the two guidewires 118, 152 may beseparated along their lengths by a body portion of the dilator 136. Insome examples, the dilator 136 can be inserted before the channelguidewire 152. According to such examples, a user can position a distalend of the channel guidewire 152 within the channel 142 defined by thedilator 136, and then proceed to slide the channel guidewire along thechannel and through the access path.

FIG. 11 depicts a subsequent step, after removal of the first sheath102, which can leave the first guidewire 118 and the dilator 136 in theaccess path, along with the channel guidewire 152 coupled thereto.

FIG. 12 shows a subsequent step, during which the second sheath 128 isinserted over the dilator 136 and the guidewire 118 runningtherethrough. As shown, the second sheath 128 can be used to dislodgethe channel guidewire 152 from the dilator 136 in a snow plow likemanner as the second sheath is inserted. To ensure proper separation ofthe channel guidewire 152 from the dilator 136, a user can firstseparate a proximal end 156 of the channel guidewire 152 from thedilator 136 prior to sliding the second sheath 128 over the dilator. Asthe sheath 128 is then moved along the dilator 136 toward the bloodvessel 113, the tip of the sheath lifts the channel guidewire 152 wireout of the channel 142 so it lays outside of the sheath. In this manner,the second sheath 128 can serve as a wedge forced between the channelguidewire 152 and the dilator 136 until the two components arecompletely separated.

FIG. 13 shows a subsequent step, after which the dilator 136 and thefirst guidewire 118 have been removed, leaving only the channelguidewire 152 and second sheath 128. Leaving the channel guidewire 152within the access path throughout the sheath exchange process depictedin FIGS. 9-13 ensures that the access path and vessel wall opening isnot lost during an operation, thus providing an additional placeholderthat may be especially desirable when large amounts of tissue, e.g., fattissue, lie between the patient's skin and the targeted blood vessel.

Sheath Introducer Kits:

FIG. 14 is a schematic illustration of a sheath introducer kit usedaccording to at least one embodiment disclosed herein. The introducerkit 144 may be referred to as a “micro-introducer kit” in some examples.The introducer kit 144 includes a guidewire 118, a dilator 122, anaccess needle 146, and a delivery assembly 148. The access needle 146,which may be echogenic or smooth, may also be hollow and is configuredto create the access path and vessel wall puncture hole prior toinsertion of the guidewire 118 or any other interventional device. Thedelivery assembly 148 may be coupled with one or more implant assembliesor devices, e.g., TAVR, TAVI, EVAR, and/or sealing assemblies, which maybe preloaded if desired in some examples. Together, the components ofthe kit 135 may be employed to form an access path to a blood vessel,introduce one or more interventional devices thereto, and facilitate theexchange of one more vascular sheaths for one or more separate vascularsheaths. Embodiments may include fewer or additional components asnecessary to perform specific vascular procedures. For example, the kit144 may also include an introducer sheath configured to feed theguidewire 118, dilator 122, and/or additional components to a bloodvessel through the access path created by the needle 146.

FIG. 15 is a schematic illustration of another sheath introducer kit.The introducer kit 150 includes the same or similar delivery assembly148, guidewire 118, and access needle 146 included in introducer kit144, but with the dilator 136 shown in FIGS. 8A-8C and an additionalchannel guidewire 152 configured to be slidably inserted into thechannel 142 defined by the dilator 136.

Notes and Examples

The present sheath exchange systems, devices, kits and methods can beused by a treating clinician during a vascular procedure. Whileapplicable to any of a variety of patient types, the present systems,devices, kits and methods may be suited for performing vascularprocedures on relatively heavy set or obese patients having a relativelythick layer of fat tissue between the skin and the targeted access pointin a blood vessel wall. More tissue movement may occur in such patientsduring a vascular procedure. By simultaneously utilizing both aguidewire and an over-the-wire, hubless or removable-hubbed dilator, thepresent methods reduce the likelihood of losing the vessel access pointand excessive blood compared to methods that only rely solely on theguidewire or a separate device, such as a guide rod. The sheaths and/orother interventional devices exchanged according to the present methodmay be small, medium or large in size.

The above Detailed Description includes references to the accompanyingdrawings, which form a part of the Detailed Description. The DetailedDescription should be read with reference to the drawings. The drawingsshow, by way of illustration, specific embodiments in which the presentsystems, devices, kits and methods can be practiced. These embodimentsare also referred to herein as “examples.”

Although the present invention has been described with reference tocertain embodiments, persons skilled in the art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the invention. For example, a wide variety of modificationsto the embodiments of the present disclosure may be made with respectto, for example, the sequence of method steps and configuration of thepercutaneous instruments employed during one or more of these steps.

The Detailed Description is intended to be illustrative and notrestrictive. For example, the above-described examples (or one or morefeatures or components thereof), can be used in combination with eachother. Other embodiments can be used, such as by one of ordinary skillin the art upon reviewing the above Detailed Description. Also, variousfeatures or components have been or can be grouped together tostreamline this disclosure. This should not be interpreted as intendingthat the unclaimed disclosed feature is essential to any claim. Rather,inventive subject matter can lie in less than all features of aparticular disclosed embodiment. Thus, the following claim examples arehereby incorporated into the Detailed Description, with each examplestanding on its own as a separate embodiment:

In Example 1, a method for replacing a first sheath, whose distal end ispositioned inside a vessel and whose proximal end is positioned outsidethe skin of a patient, with a second sheath can comprise inserting adilator over a guidewire and into the first sheath until a distal end ofthe dilator and a distal end of the guidewire are positioned inside thevessel; removing the first sheath, thereby leaving the dilator and theguidewire in place; passing the second sheath over the dilator and theguidewire until a distal end of the second sheath is positioned insidethe vessel; and removing the dilator and the guidewire, thereby leavingthe second sheath in place.

In Example 2, the method of Example 1 can optionally further compriseinhibiting patient blood loss through a puncture hole in a wall of thevessel using the combination of the dilator and the guidewire tosubstantially fill the puncture hole.

In Example 3, the method of any one of Examples 1 or 2 can optionally beconfigured such that the dilator is hubless and defines a lumenconfigured to receive the guidewire.

In Example 4, the method of any one of Examples 1 or 2 can optionally beconfigured such that the dilator includes a removable hub and defines alumen configured to receive the guidewire.

In Example 5, the method of any one or any combination of Examples 1-5can optionally be configured such that the dilator comprises a middleportion having an approximately constant diameter, and a portion of thedistal end of the dilator and a proximal end of the dilator are tapered.

In Example 6, the method of Example 5 can optionally be configured suchthat the tapered portion of the distal end of the dilator comprises aradiopaque band.

In Example 7, the method of Example 5, wherein one or more portions ofthe dilator include a radiopaque element.

In Example 8, the method of Example 5 can optionally be configured suchthat the diameter of the middle portion of the dilator is approximatelythe same size as a puncture hole in a wall of the vessel.

In Example 9, the method of any one or any combination of Examples 1-8can optionally be configured such that the dilator is about 30 cm toabout 70 cm long, inclusive.

In Example 10, the method of any one or any combination of Examples 1-9can optionally be configured such that the dilator comprises anapproximately uniform stiffness profile along a length of the dilator.

In Example 11, the method of any one or any combination of Examples 1-10can optionally be configured such that the first sheath is a proceduralintroducer sheath configured to channel at least one interventionaldevice to the vessel.

In Example 12, the method of Example 11 can optionally be configuredsuch that the interventional device comprises a transcatheter aorticvalve replacement assembly.

In Example 13, the method of any one or any combination of Examples 1-12can optionally be configured such that the second sheath is a sealingintroducer sheath configured to channel an implant assembly to thevessel, the implant assembly configured to seal a puncture hole createdin a wall of the vessel.

In Example 14, the method of any one or any combination of Examples 1-13can optionally be configured such that the guidewire defines a lumen anda length that is greater than a length of the dilator.

In Example 15, the method of Example 14 can optionally be configuredsuch that the length of the guidewire is about 30 cm to about 80 cm,inclusive.

In Example 16, the method of any one or any combination of Examples 1-15can optionally be configured such that the distal end of the guidewireextends at least about 10 cm within a lumen of the vessel afterplacement therein.

In Example 17, the method of any one or any combination of Examples 1-16can optionally be configured such that an external diameter of theguidewire is about 0.01 inches to about 0.04 inches, inclusive.

In Example 18, the method of any one or any combination of Examples 1-17can optionally be configured such that the vessel comprises a portion ofthe femoral artery.

In Example 19, the method of any one or any combination of Examples 1-18can optionally be configured such that the vessel comprises a portion ofthe radial artery.

In Example 20, the method of any one or any combination of Examples 1-19can optionally be configured such that a distance between an outersurface of a wall of the vessel and the skin of the patient is about 1cm to about 10 cm.

In Example 21, the method of any one or any combination of Examples 1-20can optionally be configured such that the dilator defines an externalchannel configured to slidably receive a channel guidewire.

In Example 22, the method of Example 21 can optionally be configuredsuch that the method further involves inserting the channel guidewireinto the external channel defined by the dilator.

In Example 23, the method of Example 22 can optionally be configuredsuch that upon removing the first sheath, the channel guidewire remainsinserted within the external channel defined by the dilator.

In Example 24, the method of Example 23 can optionally be configuredsuch that passing the second sheath over the dilator and the guidewirefurther involves removing the channel guidewire from the externalchannel using the second sheath.

In Example 25, the method of Example 24 can optionally be configuredsuch that removing the dilator and the guidewire further involvesleaving the channel guidewire in place within the patient.

In Example 26, the method of any one or any combination of Examples21-25 can optionally be configured such that a portion of the distal endof the dilator and a portion of a proximal end of the dilator aretapered and the external channel extends onto the distal and proximalends.

In Example 27, the method of any one or any combination of Examples21-26 can optionally be configured such that the guidewire and thechannel guidewire are substantially equally dimensioned.

The scope of the present systems, devices, kits and methods should bedetermined with reference to the appended claims, along with the fullscope of equivalents to which such claims are entitled. In the appendedclaims, the terms “including” and “in which” are used as theplain-English equivalents of the respective terms “comprising” and“wherein.” Also in the following claims, the terms “including” and“comprising” are open-ended; that is, a system, kit or method thatincludes features or components in addition to those listed after such aterm in a claim are still deemed to fall within the scope of that claim.Moreover, the terms “first,” “second” and “third,” etc. in the followingclaims are used merely as labels, and such terms not intended to imposenumerical requirements on their objects.

The Abstract is provided to allow the reader to quickly ascertain thenature of the technical disclosure. It is submitted with theunderstanding that it will not be used to interpret or limit the scopeor meaning of the claims.

What is claimed is:
 1. A method, comprising: positioning a distal end of a first sheath inside a vessel and a proximal end of the first sheath outside the skin of a patient; inserting a dilator over a guidewire and into the first sheath until a distal end of the dilator and a distal end of the guidewire are positioned inside the vessel, wherein the dilator defines an external channel configured to slidably receive a channel guidewire; inserting the channel guidewire into the external channel defined by the dilator; removing the first sheath, thereby leaving at least the dilator and the guidewire in place; passing a second sheath over at least the dilator and the guidewire until a distal end of the second sheath is positioned inside the vessel; and removing the dilator and the guidewire, thereby leaving at least the second sheath in place.
 2. The method of claim 1, further comprising inhibiting patient blood loss through a puncture hole in a wall of the vessel using the combination of the dilator and the guidewire to substantially fill the puncture hole.
 3. The method of claim 1, wherein the dilator is hubless and defines a lumen configured to receive the guidewire.
 4. The method of claim 1, wherein the dilator comprises a middle portion having an approximately constant diameter, and wherein a portion of the distal end of the dilator and a proximal end of the dilator are tapered.
 5. The method of claim 4, wherein one or more portions of the dilator include a radiopaque element.
 6. The method of claim 1, wherein the dilator is about 30 cm to about 70 cm long, inclusive.
 7. The method of claim 1, wherein the dilator comprises an approximately uniform stiffness profile along a length of the dilator.
 8. The method of claim 1, wherein the second sheath is a sealing introducer sheath configured to channel an implant assembly to the vessel, the implant assembly configured to seal a puncture hole created in a wall of the vessel.
 9. The method of claim 1, wherein the guidewire defines a lumen and a length that is greater than a length of the dilator.
 10. The method of claim 9, wherein the length of the guidewire is about 30 cm to about 80 cm, inclusive.
 11. The method of claim 1, wherein the distal end of the guidewire extends at least about 10 cm within a lumen of the vessel after placement therein.
 12. The method of claim 1, wherein an external diameter of the guidewire is about 0.01 inches to about 0.04 inches, inclusive.
 13. The method of claim 1, wherein upon removing the first sheath, the channel guidewire remains inserted within the external channel defined by the dilator.
 14. The method of claim 13, wherein passing the second sheath over the dilator and the guidewire further comprises removing the channel guidewire from the external channel using the second sheath.
 15. The method of claim 14, wherein removing the dilator and the guidewire further comprises leaving the channel guidewire in place within the patient.
 16. The method of claim 1, wherein a portion of the distal end of the dilator and a portion of a proximal end of the dilator are tapered and the external channel extends onto the distal and proximal ends.
 17. The method of claim 1, wherein the guidewire and the channel guidewire are substantially equally dimensioned. 